Follow the below steps:-
Step #1 : Go to Roster Slider Settings (Default Settings) => Basic Settings Tab => Miscellaneous => Feature Support Needed => Select ‘Scroll Value will differ from Visible items value’ => Save Settings
Step #2 : Go to Roster Slider Settings => Basic Settings Tab => Refer ‘Number of Items to Scroll in one transition’ => Enter 1 instead of 3 (this value would be different from ‘Number of Items Visible in One Set’ settings just above it) => Save the Settings
You are done!!